Pulleys such as drive pulleys (both front-side and back-side), idler pulleys, tensioner pulleys, and the like are frequently employed for automotive use, e.g. to drive or tension a belt of a drive system. The belt drive system can include a driver pulley and one or more idler pulleys and a belt trained around the belt surface of each of the various pulleys. The belt surface may be, for example, smooth, deep V-shaped, cogged or multi-ribbed.
In such automotive and other industrial applications, contaminants such as dust, sand, salt, and/or other foreign matter can find a way into the pulley's bearing. Bearings wear more quickly when left open to contaminants, thereby reducing the lifespan of the bearing. Contaminants can also cause the ball or rolling element to make excessive noise or even seize up. Seizing can cause the driving belt to break or fall off as a result of the belt sliding on a locked pulley.
A bearing seal is a first line of defense against contaminants, but is often not enough. Additional seals or sealing methods are often used to improve the defense against contaminants, like those described in U.S. Pat. No. 4,916,750, U.S. Pat. No. 3,177,020, and U.S. Pat. No. 2,747,689 directed to double seals. These double seals, however, are included in the bearing, rather than as an external seal.
Conventional labyrinth seals are one example of an external seal or bearing shield that reduces the amount of contaminants reaching the bearing. The problem with a labyrinth seal is that they still provide an open pathway underneath the seal, regardless of how small the pathway, for contaminants to reach the bearing.
Other seal designs utilize bearing shields that are pressed into the bore of the pulley that houses the bearing. One problem with such designs is the difficulty of installation, which typically requires a special tool to press the bearing shield into the bore. Additionally, the bore requires tight tolerances for securely retaining the bearing shield, which may be difficult to manufacture consistently. These aforementioned seal designs are not ideal.
Accordingly, it is desired to have a bearing shield that improves the defense against contaminants, while also being easier to install and/or manufacture.